Synthesis, characterization, and photochemical properties of chromophores containing photoresponsive azobenzene and stilbene

In this article, we describe the synthesis of two azobenzene and two stilbene-based diacetylene chromophores containing terminal electron-donating (OCH3) and electron-withdrawing (NO2) terminal groups with esterification reactions. The target compounds were characterized by NMR, X-ray diffraction (XRD), absorption, and photoluminescence spectroscopies. We investigated the structural effects of these photochromic compounds on the EZ photoisomerization and 1,4-addition under UV irradiation. 4-[(4-Nitrophenyl)-diazenyl]phenyl pentacosa-10,12-diynoate, incorporating the electron-withdrawing nitro group (NO2), underwent the fastest rate of Z-to-E isomerization in darkness via a rotation mechanism. Our results demonstrate that self-assembled azobenzene Z isomers exhibited enhanced fluorescence under UV irradiation. XRD spectroscopy identified bilayer packing by the polydiacetylene films after 1,4-addition. Chromophores comprising the diacetylene group presented moderate photochromic stability upon 1,4-addition, changing from their original yellowish color to form a blue phase. These synthesized compounds may be useful in the development of new and unique functional materials that exhibit bistable photochromism. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012